1. Field of the Invention
The present invention relates generally to improvements in turbine construction and, more particularly, but not by way of limitation, to turbines used for providing a source of motive power.
2. Brief Description of the Prior Art
As sources of motive power, turbines offer several distinct advantages over piston engines. For example, where both the turbine and the piston engine are designed to be operated by the internal combustion of a fuel, the turbine is much less sensitive to the type of fuel that might be used. In general, a turbine can be easily adapted to use substantially any type of fuel; for example, a turbine can be easily operated using powdered coal. The piston engine, on the other hand, can be adapted to use such fuels as powdered coal only with difficulty and, because of the difficulty involved, only at relatively high expense.
In addition, the turbine generally operates at a higher efficiency than can a piston engine. A major factor causing reduced efficiency for a piston engine is that the pistons are brought to rest at the end of each stroke within the cylinders in which the pistons are disposed so that energy must be expended to start the piston moving again, in the opposite direction, as each new stroke is commenced. This energy is derived from the fuel being used to operate the engine so that the overall efficiency of the engine is lowered by the necessity of its expenditure. In the turbine, the vanes that the combusting fuel works against to turn the turbine shaft upon which the vanes are mounted are always moving in the same direction so that this efficiency decrease factor of the piston engine is avoided in the turbine engine.
While the loss of efficiency caused by the reciprocating motion of the pistons of a piston engine can be avoided by causing the piston to move continuously in one direction; for example, by adopting a design such as that found in the Wankel engine, such solution gives rise to yet another problem that results in a lowering of the efficiency of the engine. In engines of the Wankel type, the spaces inside the engine in which the fuel is burned have a relatively low volume to surface area ratio which results in large losses of heat through the walls of the engine. A resulting cooling of the combustion gases by conduction rather than adiabatic expansion of the gases gives rise to a lowering of the efficiency of the engine. That is, the increase in efficiency resulting from the continuous rotation of the piston in one direction is offset by a decrease in efficiency stemming from the geometry of the engine necessary to cause the engine to operate with the piston moving in one direction. The turbine engine, on the other hand, can easily be constructed to have a much larger volume to surface area ratio to eliminate this problem with the Wankel engine.
Despite the advantages of the turbine engine over the piston engine, there are applications in which the turbine engine has not been extensively used with an example of such an application being the use of a turbine as the prime mover of an automotive vehicle. While some turbine powered automobiles and trucks have been built, such vehicles are not in widespread use. This limitation on the use of the turbine stems from a basic characteristic of turbine engines. Because of the lack of closed combustion chambers in a turbine, turbine engines produce low torque when operated at low speed. The present invention overcomes this problem by providing a turbine with the constant displacement characteristics of the piston engine while avoiding the problems that reduce the efficiency of such engines and, at the same time, retaining the capability of the turbine engine to be operated using a variety of fuels including powdered, lowgrade coal.